Community-acquired
pneumonia (CAP) continues to cause significant morbidity worldwide, and the principal bacterial pathogens (Streptococcus pneumoniae and Haemophilus influenzae) have acquired numerous resistance mechanisms over the last few decades. CAP treatment guidelines have suggested the use of broader spectrum agents, such as antipneumococcal
fluoroquinolones as the
therapy for at-risk patient population. In this report, we studied 3087 CAP isolates from the SENTRY Antimicrobial Surveillance Program (1999-2005) worldwide and all
respiratory tract infection (RTI) isolate population of pneumococci (14665 strains) grouped by antibiogram patterns against a new des-F(6)-quinolone,
garenoxacin. Results indicated that
garenoxacin was highly active against CAP isolates of S. pneumoniae (MIC(90), 0.06 microg/mL) and H. influenzae (MIC(90), < or =0.03 microg/mL). This
garenoxacin potency was 8- to 32-fold greater than
gatifloxacin,
levofloxacin, and
ciprofloxacin against the pneumococci and >99.9% of strains were inhibited at < or =1 microg/mL (proposed susceptible breakpoint).
Garenoxacin MIC values were not affected by resistances among S. pneumoniae strains to
penicillin or
erythromycin; however, coresistances were high among the
beta-lactams (
penicillins and
cephalosporins),
macrolides,
tetracyclines, and
trimethoprim/sulfamethoxazole. Analysis of S. pneumoniae isolates with various antimicrobial resistance patterns to 6
drug classes demonstrated that
garenoxacin was active against >99.9% (MIC, < or =1 microg/mL) of strains, and the most resistant pneumococci (6-drug resistance, 1051 strains or 7.2% of all isolates) were completely susceptible (100.0% at < or =1 microg/mL) to
garenoxacin (MIC(90), 0.06 microg/mL). These results illustrate the high activity of
garenoxacin against contemporary CAP isolates and especially against multidrug-resistant (MDR) S. pneumoniae that have created therapeutic dilemmas for all RTI presentations.
Garenoxacin appears to be a welcome addition to the CAP treatment options, particularly for the emerging MDR pneumococci strains.